Missing controlplanemachineset resource in IPI RHOCP 4 cluster

Solution Verified - Updated

Environment

  • Red Hat OpenShift Container Platform (RHOCP)
    • 4
  • ControlPlaneMachineSet
  • Control Plane

Issue

  • When trying to adjust the resource sizes for the control plane, the responsible custom resource controlplanemachineset is not present in the OpenShift cluster.

Resolution

Starting with OpenShift 4.12, control plane machine sets were introduced to provide management capabilities for the control plane machines. Refer to getting started with control plane machine sets for additional information.

The supportability of the ControlPlaneMachineSets depends on the OpenShift version and the cloud provider. Refer to supported cloud providers for the supportability matrix for OpenShift 4.12, and change the documentation version for different OpenShift versions.

For some OpenShift and cloud provider combinations, while the ControlPlaneMachineSets are supported, it is needed to manually create them or manually activate them (as shown in the table linked above). Refer to the respective documentation version for additional information about creating ControlPlaneMachineSets resources, for OpenShift 4.12 it is in creating a control plane machine set custom resource. For specific examples:

Root Cause

Starting with OpenShift 4.12, control plane machine sets were introduced to provide management capabilities for the control plane machines. They are similar to what compute machine sets provide for compute machines.

For some OpenShift and cloud provider combinations, while the ControlPlaneMachineSets are supported, it is needed to manually create them or manually activate them.

Diagnostic Steps

  • Verification of the ControlPlaneMachineSet custom resource (CR) existence and status is possible with the following command:

    $ oc get controlplanemachineset.machine.openshift.io cluster --namespace openshift-machine-api

An Active result confirms the presence and activation of the ControlPlaneMachineSet CR, requiring no further action.
An Inactive result indicates the existence of the ControlPlaneMachineSet CR, but its non-activation.
A NotFound result signals the absence of an existing ControlPlaneMachineSet CR.

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